SUMMARY After Plasma reset my external monitor's wallpaper and layout settings (bug 427861), I needed to change them back. So I launched System Settings, and... spent several minutes searching for "desktop", "wallpaper", folder", then browsing through all the plausible categories in the left-hand navigation. Nothing!? I remembered that these settings are per-display, so I found Display Configuration in System Settings and tried to access them here. Nope! Obviously the workaround is to right-click on the desktop on the display you want to configure, and choose Configure Desktop and Wallpaper... But there is no good reason for this not to be accessible from System Settings. STEPS TO REPRODUCE 1. Launch System Settings and try to find the layout (Desktop or Folder View) and Wallpaper for your display(s). OBSERVED RESULT You can't, Desktop Settings are not in System Settings. When you do find Desktop Settings, it looks like everything else in System Settings, so months later when you need to fix them again, you look in System Settings. EXPECTED RESULT These should be in System Settings along with (almost) everything else. If the counter-argument is that these are per-display settings, a) Display Configuration is in System Settings. You could have an affordance to launch these settings from the monitor display gadget that shows the display layout or reuse the monitor display gadget in Desktop Settings to launch the desktop settings for each display. b) I _don't_ want these settings to be per-display. I would love to be able to see them listed for each display one after the other, and have an "Apply to all displays" button, or have a toggle "Different settings for each display" that when unchecked only shows the single global settings. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 34 KDE spin KDE Plasma Version: 5.22.3 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 on Wayland ADDITIONAL INFORMATION There _is_ a wallpaper chooser in System Settings, in Screen Locking > Appearance Configure... > Wallpaper type. But not for the desktop. Until Desktop Settings is available in System Settings, there could be some help text guiding users to them, e.g. a hack adding to Display Configuration the text "To set a display's desktop layout and wallpaper, right-click on the display's background to bring up its context menu and choose Configure Desktop and Wallpaper..." and make System Settings show this panel when you search it for terms like Folder and Wallpaper.
There's a button to open the wallpaper settings on the start page of systemsettings that opens the dialog of the screen that the window is on. Marking as resolved fixed since it's similarish to your option a)